Parallel beam microradiography with x-ray image magnification has been successfully applied to the radiography of carious lesions in human teeth specimens, in vitro. New details of structural features revealed in these microradiographs show that this technique can be used to advantage in the quantitative study of mineralization and demineralization of hard dental tissues. These preliminary studies were conducted using a radiographic system designed for 8 keV x-rays, which is not the optimum energy for the sample thickness and materials of interest. The aim in this proposal is the development of instrumentation, primarily crystal x-ray optics, specifically matched to the requirements of real time dental microradiography. Such a microradiography capability would guarantee sufficient resolution and contrast to detect and follow small differences in the mineral density of specimens whose thickness approaches one millimeter. A working dental microradiographic system, operating in the x-ray energy range 20 - 25 keV, will be constructed with a wide range of magnifications and its limits of resolution and sensitivity will be determined, using dental specimens. The immediate benefits of such a development to the dental health community are: (1) The application of the microradiographic technique to current and future areas of dental research because of its greatly improved resolution and flexibility over conventional contact microradiography. (2) The possibility of following small structural changes in hard tissue structure in real time. (3) The impetus which this microradiographic capability will give to the realization of real time dental tomography. (4) High resolution radiography for the study of peridontally diseased alveolar bones and other hard tissues.